slepc3.21.1 20240426
BVMultColumn
Computes y = beta*y + alpha*X*q, where y is the jth column of X.
Synopsis
#include "slepcbv.h"
PetscErrorCode BVMultColumn(BV X,PetscScalar alpha,PetscScalar beta,PetscInt j,PetscScalar *q)
Logically Collective
Input Parameters
 X   a basis vectors object

 alpha   first scalar

 beta   second scalar

 j   the column index

 q   an array of scalars

Notes
This operation is equivalent to BVMultVec() but it uses column j of X
rather than taking a Vec as an argument. The number of active columns of
X is set to j before the computation, and restored afterwards.
If X has leading columns specified, then these columns do not participate
in the computation. Therefore, the length of array q must be equal to j
minus the number of leading columns.
Developer Notes
If q is NULL, then the coefficients are taken from position nc+l of the
internal buffer vector, see BVGetBufferVec().
See Also
BVMult(), BVMultVec(), BVMultInPlace(), BVSetActiveColumns()
Level
advanced
Location
src/sys/classes/bv/interface/bvops.c
Index of all BV routines
Table of Contents for all manual pages
Index of all manual pages